toolchain/arm: drop generic and old, add fa526/626, unify strongarm

* Add Faraday FA526/626 as suggested on bug #1291
Note however that these cores are v4 and NOT v4t.

* Make the sa110 & sa1110 cores -> strongarm since they're the same.

* Drop all of the ARM variants lower than v4 including generic, there's
no point in supporting obsolete targets.

* Fix uClibc USE_BX logic, it was always on, this would break the new
FA526/626 support and broke StrongARM since it's a v4 core.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Acked-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>